21445866636 has 24 divisors (see below), whose sum is σ = 50042729520. Its totient is φ = 7148283072.

The previous prime is 21445866593. The next prime is 21445866661. The reversal of 21445866636 is 63666854412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 447970 + ... + 493526.

It is an arithmetic number, because the mean of its divisors is an integer number (2085113730).

Almost surely, 2^21445866636 is an apocalyptic number.

It is an amenable number.

21445866636 is an abundant number, since it is smaller than the sum of its proper divisors (28596862884).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21445866636 is a wasteful number, since it uses less digits than its factorization.

21445866636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84793 (or 84791 counting only the distinct ones).

The product of its digits is 4976640, while the sum is 51.

The spelling of 21445866636 in words is "twenty-one billion, four hundred forty-five million, eight hundred sixty-six thousand, six hundred thirty-six".